Sealing technique for decreasing the time it takes to hermetically seal a device and the resulting hermetically sealed device

ABSTRACT

A sealing method for decreasing the time it takes to hermetically seal a device and the resulting hermetically sealed device (e.g., a hermetically sealed OLED device) are described herein. The sealing method includes the steps of: (1) cooling an un-encapsulated device; (2) depositing a sealing material over at least a portion of the cooled device to form an encapsulated device; and (3) heat treating the encapsulated device to form a hermetically sealed device. In one embodiment, the sealing material is a low liquidus temperature inorganic (LLT) material such as, for example, tin-fluorophosphate glass, tungsten-doped tin fluorophosphate glass, chalcogenide glass, tellurite glass, borate glass and phosphate glass. In another embodiment, the sealing material is a Sn 2+ -containing inorganic oxide material such as, for example, SnO, SnO+P 2 O 5  and SnO+BPO 4 .

CLAIMING BENEFIT OF PRIOR FILED U.S. APPLICATIONS

This patent application is a continuation application of U.S. patentapplication Ser. No. 11/820,855, now U.S. Pat. No. 7,722,929, filed Jun.21, 2007, which is a continuation-in-part application of U.S. patentapplication Ser. Nos. 11/207,691 filed on Aug. 18, 2005 and entitled“Method for Inhibiting Oxygen and Moisture Degradation of a Device andthe Resulting Device”, and 11/803,512 filed on May 15, 2007 nowabandoned and entitled “Low Temperature Sintering using Sn²⁺ ContainingInorganic Materials to Hermetically Seal a Device”. The contents ofthese documents are hereby incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a sealing method for decreasing thetime it takes to hermetically seal a device and the resultinghermetically sealed device. Examples of the hermetically sealed deviceinclude a light-emitting device (e.g., organic emitting light diode(OLED) device), a photovoltaic device, a thin-film sensor, an evanescentwaveguide sensor, a food container and a medicine container.

BACKGROUND

Transport of oxygen and/or water through laminated or encapsulatedmaterials and their subsequent attack of an inner material within adevice represents two of the more common degradation mechanismsassociated with many devices including, for example, light-emittingdevices (OLED devices), thin-film sensors, evanescent waveguide sensors,food containers and medicine containers. For a detailed discussion aboutthe problems associated with the penetration of oxygen and water intothe inner layers (cathode and electro-luminescent materials) of an OLEDdevice, reference is made to the following documents:

-   Aziz, H., Popovic, Z. D., Hu, N. X., Hor, A. H., and Xu, G.    “Degradation Mechanism of Small Molecule-Based Organic    Light-Emitting Devices”, Science, 283, pp. 1900-1902, (1999).-   Burrows, P. E., Bulovic., V., Forrest, S. R., Sapochak, L. S.,    McCarty, D. M., Thompson, M. E. “Reliability and Degradation of    Organic Light Emitting Devices”, Applied Physics Letters, 65(23),    pp. 2922-2924.-   Kolosov, D., et al., Direct observation of structural changes in    organic light emitting devices during degradation. Journal of    Applied Physics, 1001. 90(7).-   Liew, F. Y., et al., Investigation of the sites of dark spots in    organic light-emitting devices. Applied Physics Letters, 1000.    77(17).-   Chatham, H., “Review: Oxygen Diffusion Barrier Properties of    Transparent Oxide Coatings on Polymeric Substrates”, 78, pp. 1-9,    (1996).

It is well known that unless something is done to minimize thepenetration of oxygen and water into an OLED device, then theiroperating lifetime will be severely limited. As a result, much efforthas been expended to minimize the penetration of oxygen and water intoan OLED device so as to help drive the OLED operation towards a 40kilo-hour lifetime, the level generally regarded as necessary so OLEDdevices can overtake older device technologies such as LCD displays asdiscussed in the following document:

-   Forsythe, Eric, W., “Operation of Organic-Based Light-Emitting    Devices, in Society for Information Device (SID) 40^(th) anniversary    Seminar Lecture Notes, Vol. 1, Seminar M5, Hynes Convention Center,    Boston, Mass., May 20 and 24, (1002).

The more prominent efforts to date that have been performed to helpextend the lifetime of OLED devices include gettering, encapsulating andusing various sealing techniques. In fact, one common way for sealing anOLED device today is to apply and heat-treat (or UV treat) differenttypes of epoxies, inorganic materials and/or organic materials to form aseal on the OLED device. For example, Vitex Systems manufactures andsells a coating under the brand name of Barix™ which is a compositebased approach where alternate layers of inorganic materials and organicmaterials are used to seal the OLED device. Although these types ofseals provide some level of hermetic behavior, they can be veryexpensive and there are still many instances in which they have failedover time to prevent the diffusion of oxygen and water into the OLEDdevice.

To address this sealing problem, the assignee of the present inventionhas developed several different sealing techniques in which sealingmaterials (e.g., low liquidus temperature inorganic materials,Sn²⁺-containing inorganic oxide materials) are used to hermetically sealan OLED device (or other type of device)(see the aforementioned U.S.patent application Ser. Nos. 11/207,691 and 11/803,512). Although thesesealing techniques and sealing materials work well to hermetically sealan OLED device (or other types of devices) there is still a desire toimprove upon these sealing techniques so that one can decrease the timeit takes to hermetically seal an OLED device (or other type of device).This particular need and other needs have been satisfied by the presentinvention.

SUMMARY

The present invention introduces a sealing method for decreasing thetime it takes to hermetically seal a device (e.g., an OLED device). Thesealing method includes the steps of: (1) cooling an un-encapsulateddevice; (2) depositing a sealing material over at least a portion of thecooled device to form an encapsulated device; and (3) heat treating theencapsulated device to form a hermetically sealed device. In oneembodiment, the sealing material is a low liquidus temperature inorganic(LLT) material such as, for example, tin-fluorophosphate glass,tungsten-doped tin fluorophosphate glass, chalcogenide glass, telluriteglass, borate glass and phosphate glass. In another embodiment, thesealing material is a Sn²⁺-containing inorganic oxide material such as,for example, SnO, SnO+P₂O₅ and SnO+BPO₄. An advantage of using thissealing method is that by cooling the un-encapsulated device one canthen increase the deposition rate that the sealing material (e.g., LLTmaterial, Sn²⁺-containing inorganic oxide material) is deposited ontothe un-encapsulated device which decreases the time it takes tohermetically seal a device (e.g., an OLED device).

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be had byreference to the following detailed description when taken inconjunction with the accompanying drawings wherein:

FIG. 1 is a cross-sectional side view of a hermetically sealed device inaccordance with the present invention;

FIG. 2 is a flowchart illustrating the steps of a sealing method fordecreasing the time it takes to hermetically seal a device in accordancewith the present invention;

FIG. 3 is a block diagram of an 85° C./85% accelerated-agingchamber/oven which was used to test the hermeticity of three deviceswhich were prepared in a similar manner except that each of them had adifferent substrate temperature during the deposition of the sealingmaterial; and

FIG. 4 is a graph which illustrates the performance of the three testeddevices which were prepared in a similar manner except that each of themhad a different substrate temperature during the deposition of thesealing material.

DETAILED DESCRIPTION

Referring to FIGS. 1-2, there are respectively illustrated across-sectional side view of a hermetically sealed device 100 and aflowchart of a sealing method 200 used to manufacture the hermeticallysealed device 100 in accordance with the present invention. As shown inFIG. 1, the hermetically sealed device 100 includes a heat-treatedmaterial 102 (e.g., heat-treated low liquidus temperature inorganicmaterial 102 or heat-treated Sn²⁺-containing inorganic oxide material102) which encapsulates and hermetically seals one or more innerlayers/components 104 that are located on a support/substrate 106.

The sealing method 200 has a cooling step 202 in which the substrate 106and possibly the inner layer(s)/component(s) 104 of an un-encapsulateddevice 100 are cooled to a temperature which is (for example):preferably <15° C., more preferably <10° C. and even more preferably <1°C. In addition, the sealing method 200 has a deposition step 204 inwhich the sealing material 102 (e.g., LLT material 102 orSn²⁺-containing inorganic oxide material 102) is deposited over theinner layer(s)/component(s) 104 located on top of the cooledsupport/substrate 106 to form an encapsulated device 100. In oneembodiment, the sealing material 102 can be deposited over the cooledinner layer(s)/component(s) 104 and the cooled support/substrate 106 ata deposition rate which is (for example): preferably ˜5 Å/second, morepreferably ˜25 Å/second, and even more preferably ˜75 Å/second. Plus,the sealing material 102 can be deposited by using any one of variety ofprocesses including, for example, sputtering, flash evaporation,spraying, pouring, frit-deposition, vapor-deposition, dip-coating,painting, rolling (for example using a film of sealing material 102),spin-coating, a co-evaporation process, a soot gun spraying process, areactive sputtering process, a laser ablation process, or anycombination thereof.

In addition, the sealing method 200 has a heat treatment step 206 inwhich the encapsulated device 100 is annealed, consolidated orheat-treated (e.g., less than three hours at less than 100° C.) to formthe hermetically sealed device 100. The heat treatment step 206 isperformed to remove/minimize defects (e.g., pores) within the depositedsealing material 102 which may be formed during the deposition step 204(note: if Sn²⁺-containing inorganic oxide material 102 is used and inparticular SnO then the sputter-deposition step 204 itself may provideall of the heat necessary for sintering the deposited material 102). Inone embodiment, the encapsulated device 100 can be heat treated at atemperature which is (for example): preferably <400° C., more preferably<200° C., even more preferably <100° C. and most preferably <40° C. Ifdesired, the cooling step 202, the deposition step 204 and the heattreatment step 206 can all be performed in an inert atmosphere or in avacuum to help ensure that a water and an oxygen-free condition ismaintained throughout the entire sealing process. This type ofprocessing environment helps to ensure the robust, long-life operationof organic electronics 104 (for example) located within the hermeticallysealed device 100.

A main advantage of the sealing method 200 is that by cooling theun-encapsulated device 100 one can then increase the deposition ratethat the sealing material 102 is deposited onto the un-encapsulateddevice 100 which decreases the time it takes to hermetically seal thedevice 100. This is important when one wants to have a high volumeoperation and manufacture a large number of hermetically sealed devices100. Examples of hermetically sealed devices 100 include alight-emitting device (e.g., OLED device), a photovoltaic device, athin-film sensor, an evanescent waveguide sensor, a food container and amedicine container.

If one is manufacturing an OLED device 100, then the inner layers 104would include cathode and electro-luminescent materials both of whichwould be located on the substrate 106. These cathode andelectro-luminescent materials 104 can be damaged if they are heatedabove for example 100-125° C. As such, the heat treatment step 206 wouldnot be possible in this particular application if a traditional material(e.g., soda-lime glass) were deposited on the OLED device 100. Because,the temperature (e.g., 600° C.) needed to remove the defects in atraditional material (e.g., soda-lime glass) would be too high and thusseverely damage the OLED device's inner layers 104. However, in thepresent invention, the heat treatment step 206 can be performed in thisparticular application because the temperature (e.g., 100° C. or less)needed to remove/minimize the defects if any that may be in thedeposited sealing material 102 is relatively low so as to not damage theOLED device's inner layers 104. To accomplish this, the sealing material102 used to encapsulate the cooled device 100 is preferably a lowliquidus temperature (LLT) inorganic material 102 or a Sn²⁺-containinginorganic oxide material 102. These sealing materials are brieflydiscussed below but for a more detailed discussion reference is made tothe co-pending U.S. patent application Ser. Nos. 11/207,691 and11/803,512.

The LLT material 102 can make this all possible because this type ofmaterial has a relatively low liquidus temperature ≦1000° C. The lowliquidus temperature means that the LLT 102 can be heat treated at arelatively low temperature that does not thermally damage the OLEDdevice's inner layer(s) 104 but still results in a pore-free film beingformed on the OLED device 100. Again, it should be appreciated that theheat treated LLT material 102 can also be used as a barrier layer on awide variety of devices 100 in addition to the OLED device 100 such as,for example, a thin-film sensor, a photovoltaic device, an evanescentwaveguide sensor, a food container, a medicine container or any type ofelectronic device that is sensitive to moisture, oxygen or other gases(note: another LLT material 102 namely tungsten-doped tinfluorophosphate glass could also be used herein and this material wasdisclosed in co-assigned U.S. patent application Ser. No. 11/544,262—thecontents of which are incorporated by reference herein).

In one embodiment, the LLT material 102 has a low liquidus temperature≦1000° C. (and more preferably ≦600° C. and even more preferably ≦400°C.). The LLT material 102 can include, for example, glass such as tinfluorophosphate glass, tungsten-doped tin fluorophosphate glass,chalcogenide glass, tellurite glass, borate glass and phosphate glass(e.g., alkali Zn or SnZn pyrophosphates). For instance, a preferred tinfluorophosphate glass has the following composition: Sn (20-85 wt %), P(2-20 wt %), O (10-36 wt %), F (10-36 wt %), Nb (0-5 wt %) and at least75% total of Sn+P+O+F (which can be melted powder targets or sputteredpressed powder targets). These LLT materials 102 are desirable forseveral different reasons including (for example):

-   -   The LLT material 102 can be devoid of heavy metals and other        environmentally undesirable materials.    -   The LLT material 102 can be durable and exhibit low dissolution        rates when immersed in water at 85° C. (<20 microns per day).    -   The LLT material 102 can contain dye molecules and can be doped        to levels as high as 8 mM (4.8×10¹⁸ cm⁻³).    -   The LLT phosphate glasses have helium permeability coefficients        4 to 5 orders of magnitude less than that of fused silica.

In addition, the Sn²⁺-containing inorganic oxide material 102 can makethis all possible because this type of material has the ability, whenconsolidated at relatively low temperatures, to form hermeticencapsulated coatings which protect the device 100. The Sn²⁺-containinginorganic oxide materials 102 differ in several respects from the tinfluorophosphate material which was one of the aforementioned LLTmaterials. First, the Sn²⁺-containing inorganic oxide materials 102 canbe heat-treated at a lower temperature than the tin fluorophosphatematerial (note: the specific tin fluorophosphate material discussedbelow with respect to FIGS. 3-4 can be heat treated at ˜120° C.).Second, the Sn²⁺-containing inorganic oxide materials 102 do not containfluorine. Thirdly, some of the Sn²⁺-containing inorganic oxide materials102, such as SnO, have melting temperature in excess of 1000° C., whichis greater than the maximum melting temperature of 1000° C. that isassociated with the tin fluorophosphate material. Fourthly, theSn²⁺-containing inorganic oxide materials 102 have differentcompositions when compared to the tin fluorophosphate material.

The Sn²⁺-containing inorganic oxide materials 102 include compositionssuch as, for example, SnO powder, blended SnO/P₂O₅-containing powders(e.g., 80% SnO+20% P₂O₅), and blended SnO/BPO₄ powders (e.g., 90%SnO+10% BPO₄). However, the Sn²⁺-containing inorganic oxide material 102can also include blended compositions that had been melted to form theappropriate sputtering target (e.g., 80% SnO+20% P₂O₅). In oneembodiment, the Sn²⁺-containing inorganic oxide materials 102 include:(1) SnO; (2) SnO and a borate material; (3) SnO and a phosphatematerial; and (4) SnO and a borophosphate material. Typically, theSn²⁺-containing inorganic oxide material 102 can contain >50% stannousoxide (and more preferably >70% stannous oxide and even morepreferably >80% stannous oxide). Plus, the Sn²⁺-containing inorganicoxide material 102 can be heat treated at <400° C. (and preferably at<200° C. and more preferably at <100° C. and even more preferably at<40° C.).

Referring to FIG. 3, there is a diagram of an 85° C./85%accelerated-aging chamber/oven 300 which was used to test thehermeticity of three devices 100 (calcium patches) which were producedusing the same tin fluorophosphate material 102 under the samedeposition conditions except that they each had a substrate 106 whichhad been cooled to a different temperature. As shown, each tested device100 had a deposited tin fluorophosphate material 102, two inner layers104 (Al and Ca) and a substrate 106 (glass substrate 106). Inparticular, each tested device 100 was made by evaporating a 100 nm Cafilm 104 on top of a glass substrate 106 (Corning Incorporated's Code1737). Then, a 150 nm Al layer 104 was evaporated onto the Ca film 104.The Al layer 104 was used because it simulates a cathode which wastypically used to produce in-house polymer light emitting diodes(PLEDs). Using a “dual-boat” customized Cressington evaporator 308R (TedPella, Calif.), the glass substrate 106 was maintained at 130° C. andapproximately 10⁻⁶ Torr during the deposition of the Ca and Al layers104. After cooling to room temperature, the vacuum was broken and thecalcium patches were extracted from the evaporator and placed in a RFsputtering vacuum system which was then pumped to 10⁻⁶ Torr.

The RF sputtering vacuum system had a temperature controlled holderwhich was used to cool the temperatures of the Ca and Al layers 104 andthe substrate 106 (note: the three tested device 100 were respectivelymaintained at 150° C., 44° C. and 14° C.). The tin fluorophosphatematerial 102 (which in this case had a composition of 39.6 SnF₂, 38.7SnO, 19.9 P₂O₅, 1.8 Nb₂O₅ mole percent) was then sputtered onto the Aland Ca layers 104 by an ONYX-3 sputtering gun (Angstrom Sciences, Pa.)under relatively fast RF power deposition conditions (˜70 W forward/1 Wreflected RF power) and high argon pressure (˜20 sccm) (see step 204 inFIG. 2). The sputtering was performed for 2 hours to obtain a film 102thickness in the range of 3-5 μm. This particular deposition rate wasestimated to be in the range of 1-5 Å/second.

Upon completion of the deposition of the Al and CA layers 104, coolingof the substrate 106 was ceased, and an internal plug-heater wasswitched on for 2 hours to raise the substrate 106 temperature above100° C. and consolidate the sputtered tin fluorophosphate material 102(see step 206 in FIG. 2). Next, the vacuum was broken and theheat-treated devices 100 were all placed in the oven 300 and held at 85°C. and 85% relative humidity. In each tested device 100, the Ca layer104 was initially a highly reflecting metallic mirror. And, if waterand/or oxygen penetrated the tin fluorophosphate material 102, then themetallic Ca 104 would react and turn into an opaque white flaky crustwhich could be quantified with an optical measurement and thus enableone to estimate the amount of time that the encapsulated device 100could theoretically operate in normal ambient conditions (note: see theaforementioned U.S. patent application Ser. No. 11/207,691 for a moredetailed discussion about the now “standardized” calcium patch test).The results of this particular experiment are discussed in detail nextwith respect to the graph shown in FIG. 4.

Referring to FIG. 4, there is a graph which illustrates the performanceof the three tested devices 100 which were produced using the same tinfluorophosphate material 102 under the same deposition conditions exceptthat they each had a substrate 106 which had been cooled to a differenttemperature. In particular, the first device 100 a was encapsulated withthe tin fluorophosphate material 102 when it had a substrate temperatureof 150° C. The second device 100 b was encapsulated with the tinfluorophosphate material 102 when it had a substrate temperature of 44°C. And, the third device 100 c was encapsulated with the tinfluorophosphate material 102 when it had a substrate temperature of 14°C. The results of this experiment clearly illustrate the superiorhermetic barrier property of the sputter deposited tin fluorophosphatematerial 102 when the substrate 106 had been cooled during the high-ratedeposition step 204 (compare the acceptable behavior of the third device100 c to the unacceptable behavior of the first and second devices 100 aand 100 b). While not wanting to be limited by theory, it is believedthat the cooling of the substrate 106 caused smaller grain sizes in thesputtered deposited tin fluorophosphate material 102 which in turnenabled the sputtered deposited tin fluorophosphate material 102 tosinter more readily and form a desirable hermetic film over the thirddevice 100 c. In contrast, the first and second devices 100 a and 100 bwere deemed unsatisfactory on the basis of the 85/85 test resultsbecause they did not survive 1000 hours within the 85/85 environment.However, the first and second devices 100 a and 100 b survived the 1000hours within the 85/85 environment when the tin fluorophosphate material102 was deposited at a slower rate as was discussed in theaforementioned U.S. patent application Ser. No. 11/207,691.

From the foregoing, it can be readily appreciated by those skilled inthe art that the present invention relates to a sealing method 200 fordecreasing the time it takes to hermetically seal a device 100 (e.g., anOLED device 100). The sealing method 200 includes the steps of: (1)cooling an un-encapsulated device 100; (2) depositing a sealing material102 over at least a portion of the cooled device 100 to form anencapsulated device 100; and (3) heat treating the encapsulated device100 to form a hermetically sealed device 100. The sealing material 102is a LLT material 102 or a Sn²⁺-containing inorganic oxide material 102.If desired multiple layers of the same or different types of the sealingmaterials 102 can be deposited on top of the device 100. As discussedabove, the sealing material(s) 102 are specifically suited forinhibiting oxygen or/and moisture degradation which is a common problemto a wide variety of devices 100 including electronic devices, foodcontainers and medicine containers. In addition, the sealing material(s)102 may be used to reduce, for example, photochemical, hydrolytic, andoxidative damage to a device 100 due to chemically active permeants.Some additional advantages and features of using the sealing material(s)102 are as follows:

A. The sealing materials 102 may be used to prepare hermetic thin film(˜2 μm) barrier layers that fulfill the most stringent impermeabilityrequirements for OLED long-lived operation (<10⁻⁶ water gm/m² per day),and may be rapidly sputter-deposited and annealed on devices (orsubstrate materials) and in some cases at extremely low temperatures(<40° C.). The devices 100 include but are not limited to:

-   -   a. Organic electronic devices        -   Organic light-emitting diodes (OLED)s        -   Organic photovoltaic devices (OPV)s        -   Organic Sensors, with or without catalysts        -   Flexible substrates for flexible flat panel devices        -   Radio frequency identification tags (RFID)s    -   b. Semiconductor electronic devices        -   Light-emitting diodes (LED)s        -   Photovoltaic devices (PV)s        -   Sensors, with or without catalysts        -   Flexible substrates for flexible flat panel devices        -   Radio frequency identification tags (RFID)s

The substrate materials include but are not limited to:

-   -   a. Polymer Materials        -   Flexible substrates for flexible flat panel devices        -   Food packaging        -   Medical packaging

B. The sealing of organic electronic devices 100 with these particularsealing materials 102 requires no introduction of oxygen or air into thechamber during the consolidation/heat treatment. The fact that nooutside oxidizing source is required to enable the sealing event,especially at low temperatures (˜40° C.), makes this sealing techniquean attractive feature for making organic electronic devices. This isespecially true since it is well known that oxygen and moisture are theprincipal degrading reactants associated with the redox andphoto-bleaching degradation reactions that adversely affect the organiclayers and/or cathode materials located within organic electronicdevices like an OLED.

C. Sputter deposition, evaporation, and other thin film depositionprocesses may be used to deposit the sealing material 102. For example,high rate deposition of Sn²⁺-containing inorganic oxide films 102 may beproduced by evaporation of metallic tin in an oxygen containingenvironment onto a rolling substrate such as plastic at very high speed.Alternatively, reactive DC sputtering of metallic tin in an oxygenenvironment may be used to produce the desired high rate deposition of aSn²⁺-containing inorganic oxide film onto a device 100. In fact, manydifferent thin film deposition techniques may be used to deposit theSn²⁺-containing inorganic oxide film 102 (and the LLT film 102) onto thedevice 100.

D. The sealing material 102 can be batched with differentpowders/dopants to create a composition designed to achieve a specificphysical-chemical property in the deposited barrier layer. Following isan exemplary list of various dopants that can be mixed with the sealingmaterial 102 to achieve a desired physico-chemical property within thedeposited barrier layer:

-   -   a. Opacity-Transparency: For instance, SnO is opaque at visible        wavelengths, but it may be doped with components such as        phosphates to yield transparent films.    -   b. Refractive Index: Dopants such as P₂O₅, BPO₄ and PbF₂ can be        used to alter the refractive index of the sealing material 102        to help optimize, for instance, the light transmission and/or        light extraction of the device 100. For example, OLED devices        100 with top emission can be optimized when the air gaps therein        are replaced with an index-matched oxide material.    -   c. Coefficient of Thermal Expansion (CTE): Dopants such as SnF₂,        P₂O₅ and PbF₂ can be used to alter the CTE of the sealing        material 102 which can help to minimize the different forms of        delamination which are commonly associated with “CTE mismatch”        problems.    -   d. Sensitization: Phosphors, quantum dots, inorganic/organic        dyes and molecules may be added to confer desired electro-optic        characteristics which are useful for device optimization. For        instance, dopants such as carbon black can be used to alter the        electro-optic character (Fermi level/resistivity) of the sealing        material 102 to improve the efficiency of the hermetically        sealed device 100 (note: if the Fermi level can be shifted        substantially then this might enable one to alter the        conductivity of the barrier film in a manner which is analogous        to the known indium-tin-oxide (ITO) systems).    -   e. Alter Solubility and Interface Wettability for Better        Adhesion Doping the sealing material 102 with dopants, such as        SnF₂, enables one to alter the miscibility of the deposited        barrier film. In desired, this concept may be further exploited        for adhesion purposes by altering the surface wet-ability of the        sealing material 102.    -   f. Scratch Resistant: Dopants such as SnO, SnF₂ and PbF₂ may be        used to confer a hardness in the sealing material 102 which may        be desirable for various devices 100.

E. Pattern-Ability: Sputter deposition, or other thin film depositionmethods, allow different patterning techniques to be used, such asshadow masking etc., to produce micro-structures having specificdielectric properties to help optimize the operation of the device 100(e.g., an organic thin film transistor (TFT) device 100 could haveinsulator gates formed thereon to help achieve a good voltage thresholdvalue).

Although several embodiments of the present invention have beenillustrated in the accompanying Drawings and described in the foregoingDetailed Description, it should be understood that the invention is notlimited to the embodiments disclosed, but is capable of numerousrearrangements, modifications and substitutions without departing fromthe spirit of the invention as set forth and defined by the followingclaims.

The invention claimed is:
 1. A method for hermetically sealing a device,said method comprising the steps of: cooling an un-encapsulated device;sputtering a target material consisting of SnO and BPO₄ to deposit asingle thin film layer of a sealing material over at least a portion ofsaid cooled device to form an encapsulated device; and wherein the thinfilm sealing material layer forms a hermetic barrier on the device. 2.The method of claim 1, wherein said low liquidus temperature inorganicmaterial has a liquidus temperature ≦1000° C.
 3. The method of claim 1,wherein said low liquidus temperature inorganic material has a liquidustemperature ≦600° C.
 4. The method of claim 1, wherein said low liquidustemperature inorganic material has a liquidus temperature ≦400° C. 5.The method of claim 1, wherein said cooling step further includescooling said un-encapsulated device to a temperature <15° C.
 6. Themethod of claim 1, wherein said cooling step further includes coolingsaid un-encapsulated device to a temperature <10° C.
 7. The method ofclaim 1, wherein said cooling step further includes cooling saidun-encapsulated device to a temperature <1° C.
 8. The method of claim 1,wherein said sputtering step further includes depositing the sealingmaterial at a deposition rate of about 5 Å/second over said at least aportion of said cooled device.
 9. The method of claim 1, wherein saidsputtering step further includes depositing the sealing material at adeposition rate of about 25 Å/second over said at least a portion ofsaid cooled device.
 10. The method of claim 1, wherein said sputteringstep further includes depositing the sealing material at a depositionrate of about 75 Å/second over said at least a portion of said cooleddevice.
 11. The method of claim 1, further comprising the encapsulateddevice.
 12. The method of claim 11, wherein said heat treating step isperformed at a temperature <400° C.
 13. The method of claim 11, whereinsaid heat treating step is performed at a temperature <200° C.
 14. Themethod of claim 11, wherein said heat treating step at a temperature<100° C.
 15. The method of claim 11, wherein said heat treating step ata temperature <40° C.
 16. The method of claim 1, wherein saidhermetically sealed device has an oxygen permeance of less than 0.01cc/m²/atm/day and a water permeance of less than 0.01 g/m²/day.
 17. Themethod of claim 1, wherein said device is a selected one of: anorganic-electronic device including: an organic emitting light diode(OLED), a polymer light emitting diode (PLED), a photovoltaic, ametamaterial, a thin film transistor; and a waveguide; aninorganic-electronic device including: a light emitting diode (LED), aphotovoltaic, a metamaterial, a thin film transistor; and a waveguide;an optoelectronic device including: an optical switch; a waveguide; aflexible substrate; a food container; and a medical container.